What do you call a name which has an adjective / describing word as part of it?
E.g. Charles the Great, Charles the Rash, Edward the Confessor, etc.
I'm reasonably sure there was a word for this .... * scratches head *
It was (and still is! :) an epithet...
any word or phrase applied to a person or thing to describe an actual or attributed quality
“Richard the Lion-Hearted” is an epithet of Richard I.